Adults with borderline personality disorder (BPD) showed excessive emotional reactions when looking at words with unpleasant meanings compared to healthy people during an emotionally stimulating task, according to NIMH-funded researchers. They also found that people with more severe BPD showed a greater difference in emotional responding compared to people with less severe BPD. The study was published in the August 1, 2007, issue of Biological Psychiatry.

Erin Hazlett, Ph.D., of the Mount Sinai School of Medicine, and colleagues measured the startle eyeblink response, a measure of emotional reactivity, in 27 people with BPD and 21 healthy people. Past research shows that people are generally more startled during unpleasant situations than during emotionally neutral ones.2 During the study, each participant was shown a random series of words, some with neutral emotional meaning (such as "collect," "regular," "actually") and some with unpleasant meanings, particularly for people with BPD (such as "hate," "lonely," "abandon"). The participants would hear a brief startling burst of static noise at unpredictable intervals—sometimes while a word was shown, sometimes between words, and sometimes not at all.

The researchers found that both groups of participants had similar startle reactions when viewing neutral words. But people with BPD were more startled than healthy adults by the static burst when looking at unpleasant words. Also, people with more BPD symptoms showed a greater difference in startle reaction when viewing unpleasant words vs. neutral words compared to people with less severe BPD. This finding suggests that unstable emotions and impulsiveness in people with BPD may be related to an exaggerated startle reflex. The researchers' study presents an objective way to measure the problems with mood and emotional responses that are hallmark symptoms of BPD, suggesting a potentially useful adjunct to self-reported information when diagnosing and treating the disorder.